Have never travelled business class [poor value for money]
I would have to agree with that, I could possibly justify twice the economy fare but not the 3-5 times multiple. Work out the difference in $ per hour and it is horrendous. Choose a good airline with suitable departure times, pay extra for an exit row seat and bring along your own comforts such as a noise cancelling headset, iPad, slippers, eye mask and neck pillow. Supplement the menu with a few treats of your own such as cheese and chocolate.
On a really long journey such as London Sydney, break the trip with a few hours in the airside transit hotel at your en route stop. A decent sleep, session in the gym and pool, and a decent restaurant meal before getting back onboard makes a nightmare journey quite bearable.
A business class ticket typically gives 1.25 times the frequent flyer miles of an economy one for 4 times the fare so status won't come that much quicker in the airlines program.